Short selling rarely thrives in a bull market, especially one this undeterred. Still, some executives lash out at investors who bet against them, like Palantir CEO Alex Karp, who called investor Michael Burry "bats**t crazy" on CNBC for shorting his stock.

The investor who became a household name after predicting the 2008 crash and inspiring the film The Big Short has made a spectacular $1.5 billion move that could spell trouble.